Screw feed centrifugal pump



Feb. v4, 1936.

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Feb. 4, 1936. A. c. DUR-DIN, JR

SCREW FEED CENTRIFUGAL PUMP Filed Augf 18, 1934 2 sheets-sweet 2INVENTOR. 7gg/fw C. wdh, J/f

BY fw K ATTORNEY.

v Patented Feb. 44, 19236 Augustus C. Durdin, Ir.: Niles Center, lll.,assigner to Chicago Pump Company, Chicago. Ill., a corporation ofIllinois Application'August 18, 1934, Serial No. 740,381

'I'his invention relates to screw feed centrifugal pumps and itsprincipal object is to provide means for eliminating binding andclogging of the ump. The pump forming the ubject matter of hisspecification is intended priiarily for pumping liquids containing solidor semi-solid matter,

as for instance sewage, paper pulp and so forth. Ordinarily a screwconveyor and co-operating comminuting means are provided for reducingthe lo solid and semi-solid matter into smaller frag4 ments before theyenter the pump impeller, and

no claim is made herein to l suchl comminuting means but fromexperiments made in actual prac-l tice, it has been found that the solidand semila solid matter collected at various parts of the pump andformed obstructionsfor the screw conveyor and the impeller, the resultbeing that the accumulated solid matter stopped the pump, and

it had to be taken apart frequently and cleaned.

l In accordance with the present invention, stationary cutting means areprovided at the several places where .the solid4 or semi-solid`matter islikely to enter clearance spaces between the pump v casing and therotating parts therein, which sta- 29 tionary cutting means' co-operatewith cutting edges of the rotatingparts to sever or cutaway from themass any piece that-would otherwise enter the clearance spaces and causea binding" action between the pump casing and the rotating 30parts'therein. By the application of the present improvements to screwfeed centrlfugalvpumps, clogging and binding have been 'elminated andthe pumps runfindenitely even when subjected to the most rigid tests.

tures hereinafter fully set forth and claimed.

An exempliflcatlon of the invention is illustrated in the drawingsaccompanying this speclflcation in which:

40 Fig. 1 is a central, vertical-longitudinal section 'through a screwfeed centrifugal pump embodying the invention;

Fig. is a vertical cross section taken on `the line Fig.,3 is a detail,fragmental cross section taken on the line 3-3 of Fig. 1;

Fig. 4, isa detail, fragmental horizontalsection taken on the line 4-4of Fig. 3; 1

50 Fig.` 5 is'a detail, fragmental, vertical section taken on the line5-5 of Fig. 3;

Fig.' 6sis a vertical lcross section taken on the line 6.-6 of Fig.' 1;lA Fig. 7 is avertical cross Section taken on the 55 niici-icfmarana Theinvention consists in the several-novel fea Fig. 8 is a detail crosssection taken on the line 8.- 8 of Fig'. 7. Y Referring to saiddrawings, the reference character I0 designates a base upon which aremounted two end brackets II, I2, containing bearing 5 `-boxes I3 inwhich is journaled the pump shaft I4.

Between the end brackets is the pump casing I5, which is composed of acylindrical part I6 and a volute part I1 communicating therewith throughIanrpening in the'discharge end of the cylindrical 10 part. A suctioninlet is enters through the side of the cylindrical part of the. pumpcasing and a dischargeoutlet I9 leads from the volute part thereof.Desirably the end brackets are formed with upright circular parts 20,2|, that comprise l5 heads for the pump casing and are bolted thereto.and the cylindrical part of the casing is formed with a circular flange22 which is bolted to the volute part andforms one head thereof. IIhe'exact form of casing construction is, however, not 20 `materlal to theinvention, broadly considered. On the heads 20, 2l are stuiilng boxesand the usualwaterseals 23 for preventing leakage around the pump shaft.'I'he end brackets II, I 2 and pump casing I5, composed of thecylindrical part 25 I6 and volute part Il, being made of separate partsbolted together, the pump casing may be adjusted clrcumferentiallyaround the axis thereof to locate the suction inlet or the dischargeoutlet or both, invertical or inclinedpositions instead of thehorizontal positio'n illustrated.' This arrangement is of a specialimportance in con- -necting the pump to the pipelines since either theincoming or outgoing line orboth lines to and from the pump may behorizontal, vertical or.

' inclined. The entire casing I5,.,or either the cylindrical part IBthereof or the volute part I1. may be rotated relative to theendbrackets to locate the discharge outlet at various desired positionsaround the axis of the casing. 40

vMounted, on the pump shaft are a screw conveyor 24 and an impeller 25formed separately or4 integrally as desired, the screw conveyor rotating,i`n` the cylindrical part of the pump casing and` the impellerrotatingin the volute part.

The screw conveyor has one or more helical blades 2S which join with theimpeller blades 2l of the iin-v peller and serve to convey solid andsemi-solid matter-to the impeller. Cooperating with the blades ofthescrew conveyor are comminutin means for cutting, breaking, tearing,shearing or otherwise eomminuting solid and semi-solidmatter that entersthe'v pump, lhere shown inthe form of bars 28, thatextexidlongitudinally along the internal face o f the cylindrical partof the /casf 55 ing and are seated m grooves formed 1n the mternal faceand secured therein by bolts 29. The

the solids and`semi-solids and feeds the coml minuted mass t9 theimpeller and the latter discharges the liquids and comminuted mass fromthe pump. No claim is made to the pump construction thus? far described,and I shall now proceed to describe the novel features whic comlprisethe present invention. Y' One of the places where the solids or semi-/slids cause a binding effect is at the clearance conveyor and the head20 of the cylindrical part ofthe casing. -Stringy material ordinarilybecomes caught on the ends of the blades and to prevent thelaccumulation of such matter with the attendant binding at this place,cutting bars 30 are let into grooves in the head 20 and secured thereinby bolts 3|. A slight clearance is left between the terminal ends of thescrew conveyor blades 26 and the head 20, and the cutting bars 30project from the internal face on the head into this clearance space andco-operate with the end edges of the blades 26 to cut or shear off anystringy material or other pieces of material that lap over the end edgesof the blades. The material being severed at the overlapping part, itis#readily fed forward by the screw conveyor and the Abinding action isentirely eliminated at this place.

Another place where the material is likely to X wrap around the bladeslis at the place where th e of the discharge en'd of the cylindricalpartici the casing (see' Fig.,5) and a cutting ring 32 is` let into the'cylinder, which ring ts tightly therein and co-operates with^therhelicalblades of vthe l screw conveyor to cut or sheavol any material that maylap over said blades at the place where the blades travel along`the edgeof the ring. It

is to 'be observed that a considerable portion of the mass is'carriedalong the internal cylindrical face of the easingby the helical bladesand some moves along the side of the'comminuting bars 28. As the'ma'ssreaches the cutting ring 32' any r.material that overlaps the helicalblades is cut or sheared off at the ring,pass ing on to the impellerwithout 'being caught around its edgeI and as`a consequence binding orclogging at this point has been eiiminatedg Another place where binding.is lightly to occur is at the clearance space between-the'impellei`blades 21 and the head 22 .of the volute i1. Stringy material and other'material is 4likely to o nd its way -into this clearance space andcause u fsutlicilent binding to stop the pump. To prevent space betweenthe helical blades 26 of the screw:

. impeller or both. i

material from entering this clearance space, I provide cutting bars 33(see Figs. 3 to 5) that are let into grooves in the internal face of thehead 22 and are secured therein by bolts 34. The cutting bars 33 projectinto the clearance space between the head and sideedges of the impellerblades and co-operate with the blades to cut or shear oi material thatoverlaps the blades, thereby enabling `the blades to dischargethesevered pieces along with the flowing liquids. Desirably the face ofthe head 22 is relieved along the cutting side of the bars 33 as at 35to facilitate the cutting action and to provide space for the cut awaypieces. The cutting bars 33 project in front of the cutting ring 32.

In the form of impellershown the blades project from a disclike wall 36,located adjacent the head 2| and narrow impeller blades 3`| similar to'the blades 21 are provided on the side of the wall 36 opposite theblades 2l. To prevent binding in the clearance space betweenl the blades31 and.'

`the head 2|, cutting bars 38 (see Fig. 7) similar to the cutting bars33 are provided on the head 2|. If desired the faces of the head 2| andthe head 20.may be relieved adjacent the cutting bars in the same manneras the face of the head 22 is relieved at the cutting bars 33 (see'Fig.4). It has been found that with the ordinary throat leading-from thevolute to the discharge inlet, the comminuted matter would clog thethroat of small pumps. To overcome this, instead of forming a throat ofcircular cross section, as usual, in small pumps I have widened thethroat considerably as at 40 (see Figs. 'I and 8) making averticallyelongated opening or passage from 35 which leads an outwardlyflaring throat, and iind that this change d oes not impair theefficiency of the pump in any manner, but does effectively preventclogging in`the throat.

. By providing cutting means at the several places 4()v where solid orsemi-solid material is likely to cause binding between the casing androtating parts.

. I have provided a pump for handling liquidscontaining solid orsemi-solid matter wherein thev possibility ofbinding or clogging isentirely elim- 45 inated. More specifically by providing cutting means on all sides of the screw propeller and impeller blades that rotate inclose proximity to stationary walls, I eliminate the possibility otclogging due to the accumulation of solids between the closely spacedrelatively rotatable parts. The pump is particularly adapted for pumpingsewage, although its use is not limited thereto as ity is highlyeillcient, for pumping liquids contain- It is also to be observed thatboth the screw pro- 00 peller andthe impeller propel comminuted solids.

It is to be understood therefore that the'term propelling element -asused-in theffollowing claims includes either a. screw conveyor oran[More or less variation of the exact details of construction ispossibleflwithout departing from the spirit of this invention; I desire,therefore' not to limit myself to the exact form of the constructionshown and described, but intend, in

. the following claims to point outfallof the inventiondisclosed herein.

' I claim as new` and desire to secure'y by Lettera Patent:

l. A pump for pumping liquids containing solids or semi-solidscomprising'a casing having a cylindrical part and a volute -pa'rt opening thereto,some of the faces of the cylindrical and volute parts being flat, ascrew conveyor rotating in the cylindrical part and an impeller rotatingin the volute part, there being an inlet'in the cylindrical part of thecasing adjacent the flat wall thereof, said screw conveyor and impellerthereto, some of the facesof the cylindrical and volute partsbeing flat,and there being an inlet 5 (in the cylindrical part, a screwconveyorjrotating in the cylindrical part of the casing, and an imseatedin grooves in said flat faces at the inlet .and co-operating with saidedge portions of the ends of the screw and impeller, and projecting intosaid clearance spaces and co-operating with said edge portions of thescrew conveyor and impeller to shear off material that is carried tosaid clearance spaces.

3. Al pump for pumping liquids containing solids or semi-solids,comprising a casing having a cylindrical part and a volute part openingthereto, some of the faces of the cylindrical and volute parts beingflat, and there being an inlet in the cylindrical part, a screw conveyorrotating in the cylindrical part of the casing, and an impeller rotatingin the volute part, said screw conveyor and impeller having edgestraveling throughout their entire extent in close proximity to the flatfaces of the casing, and means for maintaining free clearance spacesbetween said flat faces of the casing and edges of the screw conveyorand impeller comprising cutting bars seated in grooves in said faces atthe inlet end of the screw vandimpeller and projectinginto saidclearance spaces screw conveyor and impeller to shear oi material thatis carried to said clearance spaces, the faces of the casing beingrelieved in front of the cutting edges of the cutting bars.

4. A pump for pumping liquids containing -solids or semi-solids,comprising a cylindrical casing having a head and a suction inletadjacent thereto, a screw conveyor rotating in said .casing with the endedge of its conveyor. blade traveling in close proximity to said head.and a cuttingbar on said head projecting into the clearance spacebetween the head and the end of the conveyor blade and co-operating withsaid end of the blade to shear oif material that is carried to saidclearance space.

5. A pump for pumping liquids containing solids or semi-solids,comprising a casing having a cylindrical part and a volute part openingthereto, the casing having a flat face joining the cylindrical part withthe volute parta screw conveyor rotating in the cylindrical part of thecasing and an impellerrotating in the volute part, and a cutting ringextending circumferentially about the screw conveyor and secured in thecylindrical part of the casingadjacent the flat wall of the volute partand co-operating with shearoff material carried to the cutting ring.

6. A pump for pumping liquids containing solids or semi-solids,comprising a casing having a cylindrical partl anda volute part openingtheretosome of the faces of which are dat, a screw conveyor rotating in4the cylindrical part of the casing and an impeller rotating in thevolute part, a comminuting bar extending longitudinally in thecylindrical part ofthe casing and a cutting ring extendingcircumferentially vabout the screw conveyor and secured in saidcylindrical part vof the casing adjacent a flat facebetweenthecylindrical and volute parts, said cutting ring co-operating with thescrew conveyor to shear off material that is'carried to the cuttingring.

7. A pump for pumping liquids containing solids or semi-solids,comprising in combination,

20 the peripheral edge of the screw conveyor to a pump casing composedof a cylindrical part and `suction inlet on the cylindrical partintermediatez its ends and a discharge outlet in the volute part. o

a screw conveyor rotating in the cylindrical part and an impellerrotating in the.volute part, the screw conveyor having blades travelingin close proximity tothe end and side wall of the cylindrical part ofthe casing, and the impeller having blades traveling in close proximityto the side walls of the volute part of the casing, and cutting bars onall of said casing walls, outlining the screw conveyor andimpellerexcept around the periphery of the impeller, said cutting barsentering the clearance spaces between the blades and casing walls, andco-operating with said blades to prevent, solid or semi-solid matterlfrom collecting and binding between any of the lcasing walls and co

